As for techniques for cultivating plants without using soil, patent literatures 1 and 2 described below are known.
The hydroponic cultivation apparatus disclosed in the patent literature 1 is provided with a plurality of cultivation beds, which have nutrient solutions for cultivation separated. Therefore, according to the hydroponic cultivation apparatus, even if a plant disease is caused in an arbitrary cultivation bed, it is possible to prevent the disease from spreading.
The purification apparatus disclosed in the patent literature 2 purifies a nutrient solution, which grows plants cultivated in hydroponics, by means of ozone and ultraviolet radiation.